1848.] MURCHISON ON THE STRUCTURE OF THE ALPS. 209 



Returning to the chief section (fig. 17), I specially call attention to 

 the ascending succession, as seen to the south-east of Burgberg, above 

 the intermediate gryphite zone (e). As on the east flank of the 

 Grimten (fig. 18), so here we see schist and thin bands of dark flyscli 

 with white veins, intercalated between the greensand and impure lime- 

 stone with the Gryphsea and the lower zone of nummulites. The 

 mineralogical transition is here equally perfect, nummulites are also 

 abundant, together with Pectens, Spondyli, and other fossils of 

 the zone, the beds being also ferriferous, but offering some local 

 peculiarities, such as small cavities in the green sandy calciferous 

 grits. This band (/) is overlaid by glossy light grey and dark 

 schists, that have been worn into a small depression, which is fol- 

 lowed by a second ridge of nummulitic rock. The mass of this is a 

 greenish, yellowish sandstone, or sandy calc grit, which graduates 

 into a hard siliceous limestone containing large Echini, Pectens, 

 Terebratulae, as well as Nummulites, and is very peculiar from the 

 small flakes of chlorite which occupy the structural divisions of some 

 of the foraminifera. Shale and thin stone bands recur in another 

 slight depression, followed by another course of nummulitic limestone 

 of grey colour, but also containing iron, whereon an ancient castle 

 stands ; then another depression in shale, &c. ; and lastly a great band 

 of nummulitic limestone of about 150 feet in thickness, which, being 

 thin-bedded, sandy, and subconcretionary in its lower parts, passes 

 up into very thick beds of hard grey limestone charged with Num- 

 mulina millecaput, Orbitolites, &;c. This limestone, when followed 

 to the Starzlach, plunges under other courses of schist and sandy 

 shale, forming part of the great overlying masses that occupy both 

 banks of the river Iller, between Sonthofen and Ober Maiselstein, 

 but which are denuded in the plain of Sonthofen. 



I may complete this ascending section of the formations in the 

 valley of the Iller by stating, that although a consecutive ascending 

 order is observable in the hills to the east, the same order cannot be 

 followed without breaks, curvatures and reversals in the chief de- 

 pression or on its western side. It is manifest, however, that all the 

 sandstones, schists and bastard limestones, which constitute the flysch 

 on both sides of the valley between Sonthofen on the north and the 

 Schwarzenberg, are parts of that great group the lower portion of 

 which inosculates with the nummulitic limestones. (See fig. 19.) 



Fig. 19. 

 Left hank of the Iller , above Sonthofen. 



N.N.W. Bolghen. Schwarzenberg. S.S.E. 



Valley of 

 Oberstdorf. 



* The small Nmnmulina placentula (Desh.), N. intermedia (D'Arch.), in this 

 band, is, I believe, the same species knoM'n in the nummulitic limestones of 



